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The relationships between the polymerization related to structure and the composition of different types of natural resins were determined. Analyses were carried out by Fourier transform infrared spectroscopy (FTIR), differential thermal analysis–thermogravimetry (DTA-TG) and hot stage microscopy (HSM). Copal specimens were collected from the Mai-Ndombe Lake, Democratic Republic of Congo, and amber pieces that came from Bitterfeld, Germany, and from Kaliningrad, Russia. FTIR spectra of copal show a vibrational band at 1643 cm−1 (C=O stretching) attributed to communic acids, while amber shows a band at 1735 cm−1 associated with ester-group vibrations and a shoulder at about 3340 cm−1, suggesting partial oxidization. DTA shows the main exothermic peak, related to the combustion, at 546–552 °C in amber and at 518 °C in copal. The derivative thermogravimetry (DTG) peaks vary in the different resin types; in amber, they occur at 333–335, 401–404 and 548–555 °C and are related to mass losses of 31, 26 and 39 mass%, respectively; copal peaks are at 394 and 507 °C, with mass losses of 71 and 27 mass%, respectively. In copal, hot stage microscopy (HSM) shows the start of sintering at 131 °C, followed by an expansion produced by the material decomposition and the generation of gases that cannot be released because of the material plastic behaviour. Finally, the increase in pressure produces an explosion that results in a lower viscosity of the liquid, which at this point can no longer support the internal pressure of gases. In amber samples, a smaller decrease in viscosity is observed and the start of sintering occurs at 150 °C with no significant change in their morphology. [ABSTRACT FROM AUTHOR]

Herbs have been used as natural remedies for disease treatment, prevention, and health care. Some herbs with functional properties are also used as food or food additives for culinary purposes. The quality and safety inspection of herbs are influenced by various factors, which need to be assessed in each operation across the whole process of herb production. Traditional analysis methods are time-consuming and laborious, without quick response, which limits industry development and digital detection. Considering the efficiency and accuracy, faster, cheaper, and more environment-friendly techniques are highly needed to complement or replace the conventional chemical analysis methods. Infrared (IR) and Raman spectroscopy techniques have been applied to the quality control and safety inspection of herbs during the last several decades. In this paper, we generalize the current application using IR and Raman spectroscopy techniques across the whole process, from raw materials to patent herbal products. The challenges and remarks were proposed in the end, which serve as references for improving herb detection based on IR and Raman spectroscopy techniques. Meanwhile, make a path to driving intelligence and automation of herb products factories. [ABSTRACT FROM AUTHOR]

Natural waters contain some carbonaceous materials referred to as dissolved organic matter, which is mainly composed of humic acids (HA). Owing to its polydispersed character related to the presence of diverse molecular size fractions (< 450 kDa to even < 1 kDa), HA displays curious reactivity in natural waters and during water treatment train. In this study, a system-based stepwise approach was tracked by characterizing HA following photolysis, adsorptive interactions, and solar photocatalysis using bare TiO2, sol–gel prepared TiO2, and their respective Cu-doped specimens complementary to kinetic evaluation on this respect. For this purpose, prior to and following each treatment, HA was monitored by dissolved organic carbon content, UV–vis parameters, and fluorescence features. Attenuated total reflection Fourier transform infrared (FTIR), surface-enhanced Raman scattering spectroscopy (SERS), XRD, SEM, EDAX XPS, and DRS were used to characterize the materials and solutions reported in this study. Most significant quantitative variations were attained in UV–vis spectroscopic parameters along with fluorescence characteristics; however, infrared and Raman profiles displayed slight deviations in qualitative measures. Differentiation between the selected photocatalyst specimens could be visualized through molecular size effects pointing out the significance of HA 10 kDa fraction. For the first time, this study reports the degradation of specific fractions of HA as a function of their molecular size fraction. Cu-TiO2 seems to photocatalyze more effectively the degradation of the diverse HA fractions due to their more extended absorption of solar light by this photocatalyst. [ABSTRACT FROM AUTHOR]

The way to analyze data in spectroscopy has changed substantially. At the same time, data science has evolved to the point where spectroscopy can find space to be housed, adapted and be functional. The integration of the two sciences has introduced a knowledge gap between data scientists who know about advanced machine learning techniques and spectroscopists who have a solid background in chemometrics. To reach a symbiosis, the knowledge gap requires bridging. This review article focuses on introducing data science subjects to non-specialist spectroscopists, or those unfamiliar with the subject. The article will explain concepts that are covered in machine learning, such as supervised learning, unsupervised learning, deep learning, and most importantly, the difference between machine learning and artificial intelligence. This article also includes examples of published spectroscopy research, in which some of the concepts explained here are applied. Machine learning together with spectroscopy can provide a useful, fast, and efficient tool to analyze samples of interest both for industrial and research purposes. [ABSTRACT FROM AUTHOR]

We investigated the temperature influence on the structural and vibrational properties of β‐HMX (β‐octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine) by using a combination of ab initio molecular dynamics and density function theory. The results indicate that the lattice constants and unit‐cell volume of HMX do not present obvious temperature effects. Most of the vibrational modes display similar hardening trend under the temperatures, suggesting that the crystal transformation of HMX under heat is through this displacement. The dependence of Infra‐red spectra on the temperature presents red‐shifted and a little decrease in the intensity of lattice vibration. This may suggest that there is a new bond formed or an old bond broken in the system if the temperature is higher than 873 K. The intensity of ratting mode caused by volumetric contraction and Raman are obviously much larger than that of the crystalline HMX at 0 K and the lattice vibrations are blue‐shifted. It demonstrates that the lattice vibrations are much more drastic. It is found that the deformation vibrations of cycle and nitro group are milder at relatively higher temperatures. This suggests that the cycle space becomes small enough to influence the HMX vibrations. [ABSTRACT FROM AUTHOR]

This paper undertakes the synthesis by slow evaporation method at room temperature of a new organic-inorganic hybrid material with the general formula [C12H13N2O]H2AsO4. The newly developed hybrid is characterized by X-ray single crystal diffraction, Infrared, Raman spectroscopy and density functional theory (DFT) calculations. At ambient temperature, this compound crystallizes in the non-centrosymmetric space group P212121 of the orthorhombic system. The structural arrangement is formed by infinite anionic chains extending parallel to the direction [100]. The organic entities are linked to these chains by N-H···O type hydrogen bonds which play an important role in the cohesion of the one-dimensional network. The optimized molecular structure, vibrational spectra and the optical properties were calculated by the DFT method using the B3LYP function with the LanL2DZ basis set. The vibrational wavenumbers were evaluated for this compound by using transferable scale factor. The first hyperpolarizability value βtot of the title compound is equal to 15.94 × 10−31 esu. Hence, the large β value calculated by the B3LYP method shows that the studied compound is a good NLO material and is suitable for future non-linear optical studies. The HOMO-LUMO energy gap and other related molecular properties are going to be discussed and reported later. [ABSTRACT FROM AUTHOR]

Glasses in the 25BaSO 4 − 30B2O 3 − (45 −x)P2O 5 − xDy2O3 system with x = 0.1, 0.3, 0.5, 0.7 and 1.0 mol% have been prepared by the melt quenching approach with the aim of using it for optical and white light application. The structural properties are examined by Fourier transform infrared and Raman spectroscopy. The amorphous state of the glasses matrices is determined by X-ray diffraction. Direct and indirect energy bandgap have been evaluated via the data found from UV–visible–near IR spectroscopy. The spectral absorption, emission and excitation are measured, and it is found that the glass doped Dy2O3 ions display good UV-excited luminescence of 4F 9 / 2 → 6 H 1 5 / 2 and 4F 9 / 2 → 6 H 1 3 / 2 transition around 480–500 and 570–600 nm corresponding to blue and yellow regions respectively. The physical parameters of the glasses have also been calculated. Infrared and Raman of the borosulfophosphate glasses revealed intense spectrum which is characterized by distinct bands. [ABSTRACT FROM AUTHOR]

Water oxidation is an essential reaction of an artificial photosystem for solar fuel generation because it provides electrons needed to reduce carbon dioxide or protons to a fuel. Earth-abundant metal oxides are among the most attractive catalytic materials for this reaction because of their robustness and scalability, but their efficiency poses a challenge. Knowledge of catalytic surface intermediates gained by vibrational spectroscopy under reaction conditions plays a key role in uncovering kinetic bottlenecks and provides a basis for catalyst design improvements. Recent dynamic infrared and Raman studies reveal the molecular identity of transient surface intermediates of water oxidation on metal oxides. Combined with ultrafast infrared observations of how charges are delivered to active sites of the metal oxide catalyst and drive the multielectron reaction, spectroscopic advances are poised to play a key role in accelerating progress toward improved catalysts for artificial photosynthesis. [ABSTRACT FROM AUTHOR]

Correlation between theoretical and experimental (infrared and Raman spectroscopies) vibrational spectra of two compounds, both with a silyl group present in their main chain and with an optically active structure (L-valine) as side group, was performed. These compounds are based in a chiral dicarboxylic acid monomer and its respective polyamide-imide, oligomer that was previously synthesized by a direct polycondensation. Spectra were recorded in the region comprised between 500 and 4000 cm−1for infrared and Raman analysis. The Raman spectra were obtained through a 1064 nm laser as excitation source. Theoretical models were carried out in order to find the optimal molecular geometry of the analyzed systems, with a complete assignment of their vibrational spectra. The Raman experimental data obtained with a Nd:YAG laser for this kind of silylated organic compounds, and the comparison between these results with the theoretical data is a useful advance in the polymer synthesis field, which can be used as reference for subsequent studies. [ABSTRACT FROM AUTHOR]

The mineral donnayite-(Y) has been studied by scanning electron microscopy with chemical analysis using EDX and vibrational spectroscopy. Multiple carbonate stretching modes are observed and support the concept of non-equivalent carbonate units in the donnayite-(Y) structure. Intense sharp bands at 464, 479 and 508 cm are assigned to YO stretching modes. Raman bands at 765 and 775 cm are assigned to the CO ν bending modes and Raman bands at 589, 611, 674 and 689 cm are assigned to the CO ν bending modes. Multiple Raman and infrared bands in the OH stretching region are observed, proving the existence of water in different molecular environments in the structure of donnayite-(Y). [ABSTRACT FROM AUTHOR]

New approaches for identifying disease resistant trees are needed as the incidence of diseases caused by non-native and invasive pathogens increases. These approaches must be rapid, reliable, cost-effective, and should have the potential to be adapted for high-throughput screening or phenotyping.Within the context of trees and tree diseases, we summarize vibrational spectroscopic and chemometric methods that have been used to distinguish between groups of trees which vary in disease susceptibility or other important characteristics based on chemical fingerprint data. We also provide specific examples from the literature of where these approaches have been used successfully. Finally, we discuss future application of these approaches for wide-scale screening and phenotyping efforts aimed at identifying disease resistant trees and managing forest diseases. [ABSTRACT FROM AUTHOR]

A brief overview on the recent applications of infrared and Raman spectroscopy in the field of art forensics is presented. [ABSTRACT FROM PUBLISHER]

The thermal decompositions of polycrystalline samples of [Ni(NH)](NO) were studied by thermogravimetric analysis with simultaneous gaseous products of the decomposition identified by a quadruple mass spectrometer. Two measurements were made for samples placed in alumina crucibles, heated from 303 K up to 773 K in the flow (80 cm min) of Ar 6.0 and He 5.0, at a constant heating rate of 10 K min. Thermal decomposition process undergoes two main stages. First, the deamination of [Ni(NH)](NO) to [Ni(NH)](NO) occurs in four steps, and 4NH molecules per formula unit are liberated. Then, decomposition of survivor [Ni(NH)](NO) undergoes directly to the final decomposition products: NiO, N, O, nitrogen oxides and HO, without the formation of a stable Ni(NO), because of the autocatalytic effect of the formed NiO. Obtained results were compared both with those published by us earlier, by Farhadi and Roostaei-Zaniyani later and also with the results published by Rejitha et al. quite recently. In contradiction to these last ones, in the first and second cases agreement between the results was obtained. [ABSTRACT FROM AUTHOR]

This paper reviews charge ordering in the organic conductors, β"-(BEDT-TTF) (TCNQ), θ-(BEDT-TTF)2X, and α-(BEDT-TTF)2X. Here, BEDT-TTF and TCNQ represent bis(ethylenedithio)tetrathiafulvalene and 7,7,8,8-tetracyanoquinodimethane, respectively. These compounds, all of which have a quarter-filled band, were evaluated using infrared and Raman spectroscopy in addition to optical conductivity measurements. It was found that β"-(BEDT-TTF)(TCNQ) changes continuously from a uniform metal to a charge-ordered metal with increasing temperature. Although charge disproportionation was clearly observed, long-range charge order is not realized. Among six θ-type salts, four compounds with a narrow band show the metal-insulator transition. However, they maintain a large amplitude of charge order (Δρ~0.6) in both metallic and insulating phases. In the X = CsZn(SCN)4 salt with intermediate bandwidth, the amplitude of charge order is very small (Δρ < 0.07) over the whole temperature range. However, fluctuation of charge order is indicated in the Raman spectrum and optical conductivity. No indication of the fluctuation of charge order is found in the wide band X = I3 salt. In α-(BEDT-TTF)2I3 the amplitude of charge order changes discontinuously from small amplitude at high temperature to large amplitude (Δρmax~0.6) at low temperature. The long-range charge- ordered state shows ferroelectric polarization with fast optical response. The fluctuation of multiple stripes occurs in the high-temperature metallic phase. Among α-(BEDT- TTF)2MHg(SCN)4 (X = NH4, K, Rb, Tl), the fluctuation of charge order is indicated only in the X = NH4 salt. α'-(BEDT-TTF)2IBr2 shows successive phase transitions to the ferroelectric state keeping a large amplitude of charge order (Δρmax~0.8) over the whole temperature range. It was found that the amplitude and fluctuation of charge order in these compounds is enhanced as the kinetic energy (bandwidth) decreases. [ABSTRACT FROM AUTHOR]

In this study, ceramic samples of lead zirconate titanate Pb(Zr0.42Ti0.58)O3 (PZT 42/58) doped with Fe (hard) and Nb (soft) were studied by Raman, infrared (IR) and THz spectroscopy in the temperature range from 900 to 20 K. From the evaluation of the IR and Raman phonons in undoped ceramics, we conclude that tetragonal PZT ceramics undergo a low-temperature phase transition to a tilted phase, revealed by anomalies in phonon parameters and the appearance of new modes. Doped samples also presented similar behaviour. The main differences between undoped and doped ceramics lie in the dielectric behaviour below phonon frequency range, where several mechanisms appear: a soft central mode (CM) located near 1 THz and two relaxations in the GHz range. Both types of doping raise the permittivity values below the phonon frequencies, not only increasing the dielectric contribution of the CM, but also modifying the dielectric response near the GHz range. Soft ceramics show higher permittivity with logarithmic increase at low frequencies, corresponding to an almost frequency-independent value of the dielectric losses below 0.1 GHz. [ABSTRACT FROM AUTHOR]

The fullerenated poly vinyl chloride was synthesized by the addition reaction of azido-substituted poly vinyl chloride with C60. Structural characterization carried out using Raman and FTIR spectroscopy confirm the presence of C60 chemically bound in the new compound. Also, the photoluminescence properties of fullerenated poly vinyl chloride are considerably changed from those of C60 [ABSTRACT FROM AUTHOR]

The comprehensive study of high-current pulsed electron irradiation effect on the structure and lattice dynamics as well as optical properties of PLZT 8/65/35 ceramics have been performed. X-ray powder diffraction studies shown the transformation of the rhombohedral perovskite structure R3m (Z = 1) into orthorhombic Pmmm (Z = 1) for the sample irradiated by one pulse (dose 4 × 1014 electrons/cm²) and, as a consequence, the changes in number of phonon modes position, oscillators strength and damping in IR and Raman spectroscopy data. However neutron powder diffraction measurements of multiple irradiated samples have not been revealed any structural distortions. Dielectric parameters have shown the increasing of real and imaginary parts of complex dielectric permittivity especially in high-temperature range (T > 100°C). In the optical properties, an essential increasing of the coefficient absorption for irradiated sample in the range from 1 to 2.5 eV and the shift of the edge of fundamental absorption to lower photon energy about 0.09 eV take place. The possible mechanisms of pulsed electron irradiation effect in relaxor PLZT ceramics are discussed. [ABSTRACT FROM AUTHOR]

Recent applications of infrared and Raman spectroscopy in the study of the metamict (or "amorphized") state, high-temperature recrystallization and radiation-induced OH species in natural zircon (ZrSiO4) and titanite (CaTiSiO5) are reviewed. [ABSTRACT FROM AUTHOR]

The Bi4I16·4(C6H9N2) 2(H2O) compound was synthesized by slow evaporation at room temperature. It exhibits a zero-dimensional (0D) tetrameric structure, comprising [Bi4I16]4− distorted octahedra, with strong I⋯I interactions among adjacent anionic clusters. We used Hirshfeld surface analysis to discuss the strength of hydrogen bonds and to quantify the inter-contacts (two-dimensional (2D) fingerprint plots). It revealed that the hydrogen bonding interactions H⋯I (56.3%), π–π stacking (11.7%), and I⋯I interactions (5.9%) play the major role in the stability of the crystal structure. The crystal morphology was simulated using Bravais–Friedel, Donnay–Harker (BFDH) and growth morphology (GM) methods. The experimental habit of the title compound was adequately reproduced by the two models. The calculated results show that the crystal morphology of the title compound in a vacuum is dominated by five facets: (020), (011), (110), (10−1), and (11−1). The (020) facet is the largest among all the facets calculated. Projection of the facet showed that there are a few polar groups on the (020) facet. In the 50–400 and 400–4000 cm−1 frequency regions, we measured the Raman and infrared spectra, respectively, of the title compound, and we assigned the observed vibration modes. [ABSTRACT FROM AUTHOR]